The use of dispersions of addition copolymers preparable by single-stage or multistage free-radical copolymerization of    a) at least one olefinically unsaturated monomer and    b) at least one olefinically unsaturated monomer different than the olefinically unsaturated monomer (a) and of the general formula IR1R2C═CR3R4  (I)      in which the radicals R1, R2, R3 and R4 each independently of one another are hydrogen atoms or substituted or unsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl or arylcycloalkyl radicals, with the proviso that at least two of the variables R1, R2, R3 and R4 are substituted or unsubstituted aryl, arylalkyl or arylcycloalkyl radicals, especially substituted or unsubstituted aryl radicals;in an aqueous medium as binders in coating materials, especially aqueous basecoat materials (cf. the German patent application DE 199 30 665 A 1), primer-surfacers and antistonechip primers (cf. the German patent application DE 199 30 067 A 1), and clearcoat materials (cf. the German patent application DE 199 30 664 A 1) is known. These dispersions are entirely or substantially free of volatile organic compounds. They may comprise transparent fillers based on silica, alumina or zirconium oxide, as described in Römpp Lexikon “Lacke und Druckfarben”, Georg Thieme Verlag, Stuttgart, 1998, pages 250 to 252, “fillers”. The German patent applications do not describe how the transparent fillers are to be specifically incorporated.
The aqueous basecoat materials known from the German patent application DE 199 30 665 A 1 and the basecoats produced from them, and also the primer-surfacers and antistonechip primers known from the German patent application DE 199 30 067 A 1, and the coatings produced from them, exhibit outstanding performance properties. However, the application properties of the aqueous basecoat materials, primer-surfacers, and antistonechip primers are in need of further improvement.
The clearcoat materials known from the German patent application DE 199 30 664 A 1 and the clearcoats produced from them likewise possess outstanding performance properties. Nevertheless, the application properties of the clearcoat materials and the scratch resistance of the clearcoats are in need of further improvement.
Nanoparticles based on alumina, silica, and zirconium oxide are known per se. They are commonly sold in the form of dispersions in alcohols such as isopropanol, ketones such as methyl isobutyl ketone, or in monomers curable with actinic radiation. If dispersions in alcohols or ketones are used, however, highly volatile organic compounds are again introduced into the aqueous coating materials, adhesives and sealing compounds. On the other hand, the dispersions based on monomers cannot be incorporated into the aqueous coating materials, adhesives, and sealing compounds.
The German patent applications DE 101 06 567.1 and DE 101 06 566.3, unpublished at the priority date of the present specification, describe aqueous coating materials based on aqueous dispersions of copolymers prepared by free-radical copolymerization of monomers (a) and (b) in a miniemulsion. These dispersions are in fact entirely or substantially entirely free of volatile organic compounds. To prepare and stabilize the miniemulsions, however, it is necessary to use comparatively large amounts of nonvolatile, ultrahydro-phobic, organic compounds, which ultimately influence the profile of properties of the coating materials and of the coatings produced from them. The dispersions may include, inter alia, nanoparticles, not specified in any detail. Moreover, there is no description of how the nanoparticles are to be incorporated into the dispersions.